The present invention relates generally to a method of applying electrically conductive printed patterns to electrically insulating substrates. More particularly, the present invention relates to a method of applying electrically conductive printed patterns, particularly conductor patterns, to electrically insulating substrates, whereby a metal-containing coating agent is transferred onto the substrate in an arrangement corresponding to the printed pattern to be generated. The coating agent is transferred under the influence of energy radiation, and is chemically metallized. The present invention also relates to a metal-containing coating agent for the application of such printed patterns to electrically insulating substrates.
German periodical "Galvanotechnik" 77 (1986) No. 1, pages 51 through 60, discloses a method for applying conductor patterns to electrically conductive (SIC) substrates wherein the transfer of the conductor pattern is undertaken with the assistance of a laser. To this end, adhesive-coated epoxy resin base material is employed as a substrate. This substrate is subjected to pretreatment with SO.sub.3 vapor phase etching with a NH.sub.3 etching stop for roughening the adhesive. A Cr (III) photosensitizer which contains chrome (III)-chloride, sodium oxalate and palladium (II)-chloride, for example, is then applied to the substrate as a metal-containing coating agent. Pd nuclei is generated in the region of the conductor pattern in the following laser image transfer, these Pd nuclei enabling a chemical or galvanic thick copper-plating after a premetallization with Ni-P and a heat treatment at 100.degree. to about 120.degree. C. Due to a thick copper-plating in copper baths working without external current and given longer exposition times, disociations of the adhesive layer from the base material can occur so that the deposited interconnects lose their adhesive foundation.
"IBM Technical Disclosure Bulletin", Vol. 15, No. 9, February 1973, page 2855, discloses a method for applying conductor patterns to ceramic substrates. The method includes applying to a green ceramic substrate a metal-containing thermoplastic powder that is subsequently exposed to a laser beam in accord with the desired conductor pattern. The laser beam melts the thermoplastic powder embedding and adhering the metal particles to the ceramic substrate. Remaining metal-containing powder that was not exposed to the laser beam can then be removed with an air jet.
These prior methods have not been entirely satisfactory. In producing conductor patterns on a substrate, numerous considerations must be taken into account. It is desirable to reduce the exposition time. Further, it is necessary for the electrically conductive pattern to be sufficiently anchored. Some previous methods of producing conductor patterns on a substrate have not been entirely satisfactory because they utilize decomposition reactions that produce environmental pollution. Some previous methods of producing these conductor patterns suffer the disadvantage of being costly.
There is therefore a need for an improved method of producing conductor patterns on a substrate, as well as an improved metal-containing coating agent for the application of such printed patterns of a substrate.